This invention relates to a wire guide for a bicycle, and more particularly to a wire guide mounted to the bicycle frame near a bottom bracket. The bottom bracket is used to connect a down tube, seat tube and chain stay of the bicycle frame, and formed in a cylindrical shape to insertably support a crank shaft through a pair of bearings, which are usually supported by threaded tubular members screwed with the bottom bracket.
Generally, some bicycles have front chain wheels and/or rear chain wheels formed in multi-stage chain wheels comprising a plurality of chain wheels of different diameters, and derailleurs provided in the vicinity of the front and/or rear chain wheels. The derailleurs are connected through control wires to control levers mounted to a handle bar or down tube at the bicycle, so that the levers are operated to control the respective derailleurs to thereby switch a driving chain to each of the different diameter chain wheels, thus changing the bicycle speed in multi-stages.
The bicycle constructed as foregoing is provided at the frame in the vicinity of the bottom bracket with wire guides for guiding the control wires extending from the levers to the derailleurs respectively.
The wire guide is conventionally mounted to the frame mostly by welding. Such a mounting method, however, is troublesome and difficult to mount the wire guide in position because the wire guide, when mounted, is apt to shift. Furthermore, it is impracticable to renew the guide after once mounted even when it wears due to friction from the wire operation.
On the other hand, there is a wire guide having mounting means of a band type and mounted therethrough to the frame, in which the wire guide has a complicated construction, is expensive to manufacture, and difficult in mounting.
In light of these problems, this invention has been designed. An object of the invention is to provide a wire guide which is simple in construction, mountable simply and accurately in position near the bottom bracket, and easily replaceable when worn.
The inventor has recognized that at both axial ends of the bottom bracket are screwed threaded tubular members for carrying a crank shaft, and designed to make use of the threaded tubular members for mounting the wire guides to the bottom bracket. The wire guide comprises a guide body having a guide groove, a support extending from the guide body axially of the bottom bracket, and a fixture provided at the end of the extending support and in continuation thereof, the fixture being narrow in width and of circular arc and approximately perpendicular to the direction of the extending support. The fixture, when the threaded tubular member is screwed with the bottom bracket, is fixedly sandwiched between one axial end face thereof and the screwed threaded tubular member or lock nut screwed therewith.
Accordingly, the present invention is capable of simply mounting the wire guide and keeping the guide groove in position without using conventional welding or bands.
These and other objects and novel features of the invention will be more apparent from the following description of an embodiment of the invention in accordance with the accompanying drawings.